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• Specific Conductivity/Total Dissolved Solids Specific conductivity (Figure 23) and total dissolved solids (Figure 24) values for the three alluvial wells have remained fairly constant over the majority of the period of record. While Conductivity and TDS values at sites TR-3 and TR-4 are consistent with values obtained during the baseline studies, these parameters and several others have elevated rapidly and remained elevated at TR-1.5 since 1995. The source of the elevated values is not readily identifiable. A few factors which may have contributed to the elevated values were mentioned in the 1996 Report (i.e., inundation of the area in late spring of 1995 and the laying of telephone cable immediately upstream of the area during the summer of 1995). Lf the elevated values resulted from those activities, the values should have returned to more historic levels during the 1996, 1997 and 1998 monitoring periods. However, the values have remained elevated. It appears that the alluvium in this area is reflecting upstream alluvial water containing high levels of TDS, possibly from an old abandoned underground mine up the Little Trout Creek drainage. This conclusion is based partially on the similarity of the water quality between TR-1.5 and WR-1. As previously discussed in the surface water section, data taken between October 1990 and August 1992 is believed to be invalid due to instrument errors. Conductivity and TDS in Well WR-1 have progressed from an elevated state each spring to a lower state in the fall for the past several years. This phenomenon was caused by infiltration of snowmelt water leaching various minerals within the unsaturated zone of reclaimed spoil. As the enriched flow was released over the course of the summer, the conductivity values lessened to that of the stagnant saturated zone. The 1996-1998 data suggests that the unsaturated zone may be almost depleted of leachate. The mounded aquifer exhibits a more diluted state each spring with a return to steady-state as the summer progresses. Calcium/Magnesium/Sodium Calcium (Figure 25) is the major cation found in all of the wells with concentrations of sodium (Figure 26) and magnesium (Figure 27) occurring in lesser quantities. TR-1.5 generally contained the lowest concentrations of cations with a slight increase occurring downstream at TR-3 and TR-4 for the majority of the record. However, elevated levels of these parameters at TR-1.5 began to occur in 1995 consistent with the elevated Conductivity and TDS levels previously mentioned. The sodium level for WR-1 of 454 mg/1 obtained during October 1991 is believed to be an analytical error. Levels measured prior to and after that sample dace do not support the high concentration and followed the expected trend. 31